Penetration resistance as affected by shallow-cut land leveling and cropping

Abstract

Land leveling is a form of soil disturbance that alters soil physical properties and is commonly conducted in fields cropped to rice ( Oryza sativa L.) to facilitate more uniform distribution of irrigation water. Few studies have been conducted on the effects of shallow-cut land leveling on spatial variation of soil penetration resistance. The objective of this study was to characterize the effects of shallow-cut land leveling and cropping on penetration resistance in a soil cropped in a rice–soybean ( Glycine max L.) rotation in the Mississippi River Delta region of eastern Arkansas, USA. The study area consisted of a 50 point grid occupying 0.36 ha of a larger field that was land leveled in April 2002. Penetration resistance (i.e., cone index, CI) was measured at 0.05 m intervals to 0.35 m with a penetrometer at each grid point before, immediately after, and roughly 1 year after land leveling. Land leveling increased ( P<0.05) CI at all depths and the variability associated with CI below the 0.05 m depth and disrupted the spatial variability and distributions of CI throughout the study area. Land leveling resulted in a 0.1 m shallower hard pan, which effectively reduced the soil volume for subsequent crop root growth by 50%. The shallower pan is agronomically significant because, despite being necessary in a rice cropping system to hold irrigation water, proper management for optimum yield of alternative non-flood-irrigated crops grown in rotation with rice will be challenging due to the altered soil physical condition following land leveling. Deep-tillage may be required following shallow-cut land leveling to help alleviate the poor soil physical condition for upland crops grown in rotation with rice.